Maybe check that the spark plug wires are firmly on the spark plugs.  Same with the fuel injector connections. 

> On May 25, 2018, at 1:42 PM, Dan N <dn92610@GMAIL.COM> wrote:
> 
> hi all,
> 
> my son's 1988 tintop 2.1 WBX has hiccups (vanagon syndrome) on the
> highway.. please help us to find what's wrong... he's on a trip from Oregon
> to Southern California
> 
> description of the van:
> - rebuilt 2.1 WBX about 6K miles ago
> - temp2 sensor replaced with rebuilt engine
> - new cat converter and muffler
> 
> before the trip:
> - new factory AFM (not a rebuilt) with pigtail filter
> - new spark plugs
> - new dist. cap and rotor
> - new air filter
> - new fuel filter
> - 02 sensor is one year old (about 6K miles)
> - timing checked and in order
> - throttle body checked and in order
> - vacuum leak checked, found none
> - a bottle of Heet in the gas tank (as we think water in the tank) -> no
> help
> 
> no hiccups on his way to So. Cal. (1K miles) but he got them once he's
> there...
> 
> we scratch our head and don't what else to do...
> 
> many thanks in advance if you could help.
> 
> dan